Turns out to have been a very quick and easy install. The trim surrounding the ignition switch and shifter pops up, and there are two tongs on the side of the switch that need to be depressed to pop the switch out. Disconnecting the switch gives more room to pull the trim up and reach the tongs on the original switch.

A point to note: the original switch P/N 12768560 has been discontinued and replaced by P/N 95480111, used by other GM products. The new part has a more blue back lighting and won't match the rest of the night-time lighting. As of this writing there were still some vendors carrying the original part with correct light color, albeit at a higher price.